NTSB Identification: ANC93FA056.
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Accident occurred Sunday, May 02, 1993 in COPPER HARBOR, AK
Probable Cause Approval Date: 12/02/1994
Aircraft: BELL 204B, registration: N204AQ
Injuries: 1 Fatal,1 Minor.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

AEROLOGGING OPERATION REQUIRED A STEEP DESCENT FLIGHT PATH FROM THE LOG PICKUP SITE AT 1200 FT ELEVATION TO THE LANDING SITE AT 70 FT ELEVATION. DESCENT ESTIMATED TO TAKE 11-12 SECS, AND DESCRIBED AS 'STRAIGHT DOWN IN AUTOROTATION AND DROPPING THE LOGS.' PILOT EXPRESSED RESERVATIONS ABOUT 'BEING ABLE TO DO IT.' FOLLOWING A DESCENT, AND WHILE IN A HOVER, THE TAIL ROTOR & 90 DEG GEAR BOX SEPARATED. METALLURGICAL EXAM REVEALED FATIGUE SIGNATURES ON GEAR BOX CASE STUDS. GEAR BOX OF MILITARY ORIGIN. RECORDED WEIGHTS INDICATED THAT THE AIRCRAFT HAD BEEN OPERATING IN EXCESS OF THE GROSS WEIGHT HOOK LIMIT. THERE WAS NO RECORD OF SURVEILLANCE BY THE POI OR PMI FROM THE FAA OFFICE HOLDING THE OPERATOR'S CERTIFICATE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

FATIGUE FAILURE OF THE TAIL ROTOR GEARBOX, AND IMPROPER HELICOPTER OPERATIONS BEING CONDUCTED BY THE OPERATOR RESULTING IN REPETITIVE AT AND OVER MAXIMUM LOADS. FACTORS IN THE ACCIDENT WERE: MATERIAL DEFECT OF THE TAIL ROTOR GEAR BOX (INADEQUATE QUALITY CONTROL) BY THE COMPANY/OPERATOR, AND INADEQUATE SURVEILLANCE OF BOTH THE COMPANY OPERATIONS AND MAINTENANCE FACILITY BY THE FAA.

Full narrative available

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